3/27/2007 Blackbody and Photoelectric Computer Lab PHY 152/162

Please assign a rating to each activity. 1 = Worthless 10 = Excellent

These links are available in the Web Links section on Moodle.

Blackbody Section

_______ 1. http://webphysics.davidson.edu/alumni/MiLee/java/bb_mjl.htm (Davidson)

After the applet loads, either click on the 15000K button or drag the peak of the spectrum until the temperature indicator shows 1.5e+004. Note the labeling of numbers on the vertical scale.

TRUE or FALSE The peak of the spectrum occurs in the visible range of wavelengths.

Click on the 5000K button or drag the peak until 5e3 is in the box. TRUE or FALSE This applet correctly indicates that the hotter object emits more energy at every wavelength.

Explain why you selected True or False for this question.

________ 2. http://csep10.phys.utk.edu/guidry/java/planck/planck.html Energy Distribution

Try various temperatures. NORM = no prevents the graph from rescaling on the vertical axis for each temperature. NORM = yes plots each graph independently with its own vertical scale. NORM = no should be used to gain an appreciation of the temperature dependence of the radiated power. NORM = yes should be used to gain an appreciation of Wien’s Law.

Photoelectric Section

_____ 3. Photoelectric Experiment http://www.chemistry.ucsc.edu/teaching/switkes/CHEM1B/Winter03/photel_new.html

What is the longest wavelength of light that will eject electrons from lead? _________

You should start with a large wavelength. Vary the wavelength until the ammeter records the motion of electrons in the circuit.

______ 4. Photoelectric Effect Animation http://jchemed.chem.wisc.edu/JCEDLib/WebWare/collection/open/JCEWWOR006/peeffect5.html After you activate the window, click on the right arrow. You should now see a page that shows a circuit and a list of options on the right side. Click on the options one at a time.

Next Week: Turn in this sheet and a one paragraph summary for a magazine or Internet article which is related to one of these topics: Blackbody, Planck’s Derivation of the Blackbody equation, Photoelectric effect, Photon, Ultraviolet Catastrophe, Dual Nature of Light

Give the magazine reference (name, date, page) or the URL of the Internet site.